High tunnels and season extension in Ohio

A high tunnel buys you September and October. What you do with the rest of the year decides whether the structure pays for itself. Ohio growers who push figs and tomatoes past the first hard freeze are working with three layers of protection, and the order in which they use them matters.

The details cited in this entry were checked on Ohio State fact sheet on hardy figs.

Ohio State University researchers ran two demonstration plantings of hardy figs near Piketon from 2017 to 2020, one in the open field and one under a high tunnel, funded through a 2017 Specialty Crop Block Grant from the U.S. Department of Agriculture by way of the Ohio Department of Agriculture. The comparison is one of the few side-by-side records of what a tunnel does to a harvest calendar in this state.

Why the open field loses the race

In 2019, figs in the open field at Piketon started ripening around early October and kept going until mid-October. Fruit growth slowed as the weather cooled and stopped on October 18 and 19, when air temperatures fell to 32°F and 31.6°F. A hard freeze on November 1 stripped the leaves, and the unripe fruit shriveled afterward.

Inside the tunnel that same year, ripening began in early September and continued into November. Same cultivars, same site, same season: roughly a month gained at the start and another month at the end. That is the whole argument for the structure.

What did the tunnel change in the numbers?

Yield moved as well as timing. Over the first three years, plants inside the high tunnel produced 2 to 5 pounds of ripe figs per plant. Plants outside produced about 1 pound.

High tunnelOpen field Ripening begins (2019)Early SeptemberEarly October Harvest endsInto NovemberMid-October Ripe fruit per plant, first three years2 to 5 poundsAbout 1 pound

The study did not run a cost-benefit analysis of the high tunnel system, so the Ohio State page does not publish a break-even figure for the structure. Growers are told plainly to weigh the high cost of a tunnel against the yield they can realistically sell.

Which figs are worth trialing in Ohio?

Two cultivars earned a recommendation from the Piketon work: Brown Turkey and Hardy Chicago. Everything else in the trial, Celeste, Fantasia, Hunt, Latizia, Lola Martin, Olympian, Violette de Bordeaux, and White Marseilles, had not produced enough data by March 2020 to support advice either way.

Brown Turkey fruits are large for a fig, averaging about 40 grams in the trials, and flavorful. Under a tunnel they tend to ripen from mid to late September until a killing freeze. In the open they may not ripen fully until early October, which is a narrow window in most of Ohio. There is a trap with this cultivar: some Brown Turkey plants sold by nurseries, particularly Californian stock, may not be the hardy type. That confusion was flagged in a North Carolina State publication in 1986 and may still exist, so trial a few plants before buying a block.

Hardy Chicago is the safer bet for Ohio conditions. The fruit is much smaller, averaging 18 grams at maturity, but it ripens about three weeks ahead of Brown Turkey. In southern Ohio you can expect to pick from early to mid-September until a killing freeze. The flavor is exceptional, with a resemblance to peach. A tunnel still helps it ripen sooner and hold fruit longer.

Do you need a pollinator wasp?

No. Figs come in three types: Common, San Pedro, and Smyrna. Both recommended cultivars are Common types and set fruit without pollination, through parthenocarpy, meaning the plant develops fruit from unfertilized ovules. The fruit carries no seeds, only partially developed ovules.

San Pedro and Smyrna types are not recommended for Ohio because the wasp that pollinates them does not survive Ohio winters. That single fact rules out most of the fig cultivars sold in warmer climates.

Where should the plants go?

Figs root shallow and wide, so keep them away from drainpipes, sewer lines, and any buried infrastructure that invasive roots could reach. They want slightly acidic soil, pH 6.0 to 6.5, loamy, well drained, and high in organic matter, in full sun.

At Piketon the plants went into raised beds with landscape fabric over them for weed control. Spacing in the tunnel was 4 feet between plants and 6 feet between rows, chosen to maximize space. That proved too tight. A plant spacing of 5 to 6 feet would be better, and rows may need 8 to 10 feet to let machinery pass. Optimum spacing for Ohio is still unknown.

Figs grow as multistemmed shrubs because new shoots rise from the base and carry the fruit. The stems are pithy in the middle and do not overwinter well. Every stem in the trial was cut to the ground, including the plants inside the tunnel.

What pests and diseases show up?

Because hardy fig is a new crop in Ohio, nobody can yet say which problems will become common here. In the Piketon trials, small brown spots appeared on leaves with symptoms resembling fig rust, though a positive identification was still pending. No insect pests were seen feeding on the plants.

Elsewhere the record is longer. Alternaria and Fusarium cause internal fruit rot in California, and fig mosaic disease, a virus that produces yellow rings on leaves and sometimes on fruit, is a worldwide concern. A University of Kentucky researcher found scale insects on a potted Celeste plant overwintered in a garage in Lexington and controlled them with a summer oil spray. Ants and birds will feed on ripe fruit, and bird damage has been photographed on Celeste.

Labeled insecticides, fungicides, and herbicides for fig are limited in Ohio because the crop is new and minor, which may push growers toward organic methods by necessity rather than preference.

How do you pick and hold the fruit?

Harvest when the fruit stem loses its rigidity and the fig droops slightly. That is the point of best flavor and sugar. Ripe figs are tender, bruise easily, and store briefly. Handle them carefully, keep them dry, and move them to shallow containers quickly.

Optimum storage is 30 to 32°F at 90 to 95 percent relative humidity. Above 41°F, softening and decay accelerate. None of that is forgiving for a crop that ripens over two months in autumn.

Can you make money on figs in Ohio?

Growing hardy figs and profiting from them are different problems. Most of the crop ripens from September to November, so a high tunnel is strongly recommended for profit in southern Ohio. Growers in central and northern Ohio should be more cautious still, since all the observations come from southern Ohio.

University of Kentucky information cited in the Ohio State work puts the target at 10 pounds of fruit per plant sold for at least $3 per pound before a grower turns a profit. Fresh figs were seen selling for about $1 each at specialty and ethnic grocery stores. The Piketon project produced no accurate economic data because of funding limits and a short project period.

Start small. Plant a few, record your own yields and your own prices, and only then scale up. The Ohio State fact sheet on hardy figs carries the full cultivar notes and references from the Piketon trials.

One number is still missing from every Ohio budget on this crop: what a tunnel costs per square foot over its service life. Until a grower fills that in with a real quote and a real yield record, the decision sits with the person paying for the steel.

About the Ohioline fact sheet: Growing Hardy Figs in Ohio is an Ohioline fact sheet from Ohio State University Extension, numbered HYG-1439. It summarizes data collected from 2017 to 2020 at the OSU South Centers near Piketon, where hardy fig cultivars were grown in both an open field and a high tunnel under a 2017 Specialty Crop Block Grant. It covers cultivar selection, pollination types, soil and site preparation, spacing, observed pests and diseases, harvest and storage, and the economics of a commercial planting.